The Web project %0 must be converted to the new Web site format. If you continue with this open from source control the project ...

The Web project %0 must be converted to the new Web site format. If you continue with this open from source control the project will be converted to a File System Web site. To convert the project into an Http Web site you will need to cancel this operation and use the Open Web Site dialog instead. Do you want to continue and convert the Web project to a File System Web site?